A platform to basin transect: carbonates in the Visé-Maastricht sedimentation area (early Carboniferous, eastern Belgium)

At the north-eastern margin of the Brabant Massif, the Visé-Maastricht sedimentation area displays an early Carboniferous transect from the shoreline to deeper water facies of a half graben system. Carbonate sedimentation... [ view full abstract ]

At the north-eastern margin of the Brabant Massif, the Visé-Maastricht sedimentation area displays an early Carboniferous transect from the shoreline to deeper water facies of a half graben system. Carbonate sedimentation dominates along this transect. Active tectonics in early Carboniferous times result in the dissection of the sedimentation area into a number of blocks with different depositional histories. Overall, the complex regional tectono-evolutionary history characterised by important palaeogeographical changes and sea-level fluctuations impacts parameter as sediment sources, facies distribution, mode of sediment transport, and sediment budgets.
Detailed facies analyses have been done for the early Warnantian (late Viséan) strata in the Berneau railroad section and a borehole at Lixhe, additional data are from the ‘s Gravenvoeren borehole and disused quarries south of Visé. In the south, the emerged tectonic blocks are partly covered by carbonate platforms stabilised at their edges by microbes-sponges-metazoan reefs. Megabreccias and scarp deposits were deposited in the immediate surroundings of the Souvré Block, seen in the quarries south of Visé. The slightly more distal Berneau section, exposes in its lower part high-density turbidites and debris flows indicating an upper slope environment. Its upper part shows the progradation of a carbonate platform. The more distal areas of the half graben system (Lixhe and ‘s Gravenvoeren boreholes) are characterised by stacking patterns of mainly fine-grained turbidite beds, representing middle- and low-density deposits. Further to the North, in the most distal parts of the half graben system (Geverik borehole) argillaceous and siliceous intercalations into fine-grained calciturbidite beds become abundant.
The sedimentary pattern observed in the studied sections can be best explained as the consequence of a complex interplay of sea-level fluctuations, spatial and temporal dynamics of submarine canyons and fans, and tectonic processes. Overall, depending on the distance to the source area, the sections show differences in their relative positions in the fan systems. A model for the possible source of the resediments shows that several decametres of thickness have been eroded on the Souvré block in lower Warnantian times, but that the overall sediment budget requires significant input from nearby sources as the eastern margin of the Brabant Massif, which are traditionally considered to be emerged and sites of non-deposition. The Visé-Maastricht sedimentation area shows an exceptional high accumulation rate of resediments in comparison to contemporaneous regions in Central Europe, which may be related to the active tectonic processes in the Visé-Maastricht area.